1. Field of the Invention
The present invention relates to an etching and cleaning apparatus and method for objects, and more particularly, to an apparatus and method for batch processes for objects such as a semiconductor wafer or a liquid crystal display (LCD) substrate.
2. Description of Related Art
Etching technology is very important for compact and complicated substrates. Etching is followed by a cleaning process.
For a wet etching process a batch type process is usually adopted since it can provide mass production and a low production cost.
FIG. 1 schematically shows an etching apparatus of a batch type according to a conventional art.
A vessel 10 containing substrates 12 has upper and lower openings 111 and 113 and is linked by many pipes. To the upper opening 111 are linked a first supplying pipe 10a and a first draining pipe 10d and to the lower opening 113 are linked a second supplying pipe 10b, a third supplying pipe 10c and a second draining pipe 10e. The first supplying pipe 10a is for supplying IPA (isopropyl alcohol), the second supplying pipe 10b for supplying etching solution, and the third supplying pipe 10c for supplying D.I. (deionized) water. The first draining pipe 10d is for draining etching solution and D.I. water, and the second draining pipe 10e is for draining IPA and D.I. water.
The etching process and rinsing process using the apparatus is explained. First, through the second and the third supplying pipes 10b and 10c, etching solution and D.I. water are supplied to the vessel 10 containing substrates 12, respectively. In some conditions only etching solution can be supplied, since D.I. water is for diluting the etching solution at this time.
Next, the substrates 12 are etched by the etching solution for some time.
Next, D.I. water is supplied through the third supplying pipe 10c so as to push the mixture of etching solution and D.I. water to the upper opening 111 for draining through the first draining pipe 10d. At this time D.I. water cleans the substrates 12.
Finally, D.I. water is drained through the second draining pipe 10e and IPA is supplied to the vessel 10 in order to dry the substrates 12.
However, referring to FIG. 2, during draining, the etching solution densities of the etching solution differ depending on the location of the interface of the etching solution and the D.I. water for cleaning. That is, in a certain instant during that process the density is high at the upper portion 12a of the vessel 10 and low at the middle portion 12b of the vessel, whereas at the lower portion 12c of the vessel 10 cleaning water such as D.I. water is filled. This density difference results in non-uniform etching of the substrate 12 depending on the position of the substrate 12.
During that time, while etching solution of high density is mixed with D.I. water for cleaning, an abnormal reaction such as an electric reaction occurs. When two metal layers on the substrate are etched in one process, some metals such as aluminum lose their electrons and some metals such as titanium receive the electrons. Donor metal is over etched, and the donee metal is etched less, which deteriorates the quality of etching.